Does Smoking Weed Cause Cancer?
Last Updated Dec 2, 2021
Whether weed can cause cancer is somewhat debated, with mild evidence that it may increase a person’s cancer risks, but not to the level smoking tobacco does. In addition, smoking weed may also potentially double a person’s chance of developing a testicular germ cell tumor (TGCT).
Marijuana is understudied, and researchers simply don’t have much of the information a smoker would ideally want. However, research is ongoing.
Lung Cancer & Smoking Marijuana
More studies need to be conducted on marijuana and its potential to cause lung cancer and other negative health conditions. For decades, the drug was difficult to study due to tight legal regulations that have only recently started to relax.
It is established that smoking marijuana has the potential to deliver harmful toxins and carcinogens that are known to harm the lungs and cardiovascular systems.
Marijuana vs. Tobacco
Tobacco, more specifically cigarette smoking, is well established to drastically increase a person’s cancer risk. In fact, the CDC says people who smoke cigarettes are between 15 and 30 times more likely to develop lung cancer or die from lung cancer than non-smokers.
In addition, cigarette smoking is linked to other types of cancers in the mouth, throat, esophagus, stomach, colon, rectum, liver, and numerous other organs.
Marijuana’s effects are admittedly much less studied, but the studies that do exist don’t suggest an increase in a person’s cancer risks that is nearly as high. A 40-year cohort study suggested heavy use, defined as using marijuana over 50 times, more than doubles a person’s risk of developing lung cancer over a 40-year follow-up period.
With that said, a 2019 systemic review and meta-analysis of various pieces of cancer research was critical of many studies, noting more long-term studies of marijuana-only smokers were needed, as many studies followed individuals who regularly used other drugs (especially tobacco).
The National Institute on Drug Abuse does not purport that lung cancer is associated with marijuana use, although they do still warn about several other health side effects it can cause, discussed more below.
How Marijuana Affects Your Lungs
Marijuana is linked to several negative side effects related to the lungs, including these:
- Large airway inflammation
- Increased airway resistance
- Lung hyperinflation
- Symptoms of chronic bronchitis
Again, more studies are needed on the specifics of how marijuana affects the body. One consistent issue is that many studies use people who smoke both cigarettes and marijuana. While that data isn’t without value, it may not accurately reflect how marijuana use might affect a non-tobacco-smoker.
Risks of Secondhand Smoke
One of the most understudied elements of marijuana exposure is exposure through secondhand smoke. While there are several understandable concerns about secondhand smoke exposure due to some similarities with tobacco smoke, which is known to cause harm, there is not much definitive information about marijuana smoke’s dangers.
There has been a link between marijuana use in a household and elevated levels of THC in children living in those households. Whether this has a significant health effect on these children isn’t yet known.
Notably, this doesn’t mean marijuana smoke should be considered safe. It has significant unknowns and worrying similarities to tobacco smoke, containing some of the same toxins. If you choose to smoke marijuana, we recommend you at least do so away from children and pets.
Other Cancer Risks
There are not many definitive links between marijuana use and other types of cancers, but again, this area is understudied. Some evidence does suggest it may increase a person’s risk of a testicular germ cell tumor (TGCT).
Differences Between Vaping, Ingesting & Applying Marijuana
Most of the above has been about smoking marijuana. As for other methods of marijuana use, there is at least some evidence they may be safer, with some caveats.
Marijuana vaping has been linked to several deaths and hospitalizations, but the actual issue appears to have been poor quality control, with a drop-off in issues following a spike in August 2019.
As a general rule, only buy products from reputable businesses selling products coming from reliable brands. Be careful making any vaping or weed purchases online, as it can sometimes be difficult to verify the source of a product is what a seller claims.
Assuming a safe, reliable device is used with quality cannabis products, there are fewer troubling substances that will be introduced into your lungs.
Similarly, ingesting marijuana or using a topical product that contains weed doesn’t involve combustion or vaporization. As a result, there should be a significant reduction in the hazardous substances you’re exposed to, especially because edibles and topical products don’t enter the lungs.
Why Do Some Cancer Patients Get Prescribed Marijuana?
While the DEA lists marijuana as a Schedule I substance, meaning they consider it highly dangerous and with no accepted medical use, many experts view this classification as inappropriate. The drug seems to help with certain symptoms related to cancer and cancer treatment, although the exact mechanism of action is not fully understood.
Marijuana has been shown in a small number of studies to help patients with nausea and vomiting as a result of chemotherapy. It can also help to treat neuropathic pain, which is pain caused by damaged nerves. Marijuana extracts may have a similar effect, as patients taking these extracts needed less pain medicine in clinical trials.
Cannabinoids may even be able to help treat cancer, but more studies on that subject are needed.
Does Marijuana Have Anti-Cancer Properties?
While many people make very broad claims about marijuana’s medicinal properties online, it is important to understand its anti-cancer potential is still being studied. Marijuana may help treat certain types of cancer.
We do know that research has shown THC and other cannabinoids slow the growth of and kill some types of cancer cells, but this was in a very controlled setting within a lab dish.
If you’re interested in utilizing marijuana in your cancer treatment, talk to your doctor.
Never use marijuana as a replacement for cancer treatment, as this may delay a doctor’s ability to treat your cancer, which can become more difficult to treat if given time to progress. The sooner you receive the attention of trained, reputable experts in cancer treatment, the better your chances of achieving the best possible results.
Association Between Marijuana Use and Risk of Cancer: A Systematic Review and Meta-analysis. (November 2019). JAMA.
Cancer. (October 2020). Centers for Disease Control and Prevention.
Marijuana and Cancer. (August 2020). American Cancer Society.
Marijuana Use and Risk of Lung Cancer: A 40-Year Cohort Study. (July 2013). Cancer Causes & Control.
Secondhand Marijuana Smoke. (October 2020). Centers for Disease Control and Prevention.
What Are Marijuana’s Effects On Lung Health? (July 2020). National Institute on Drug Abuse.
Outbreak of Lung Injury Associated with the Use of E-Cigarette, or Vaping, Products. (February 2020). Centers for Disease Control and Prevention.
Vaping Is Still A Less Harmful Consumption Method Than Smoking. (April 2021). Forbes.
What Are the Risk Factors for Lung Cancer? (October 2021). Centers for Disease Control and Prevention.
Cannabinoids in Cancer Treatment: Therapeutic Potential and Legislation. (February 2019). Journal of the Association of Basic Medical Sciences.
The Effectiveness and Safety of Medical Cannabis for Treating Cancer Related Symptoms in Oncology Patients. (May 2022). Frontiers in Pain Research.
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